DDL、DML、DCL、TCL基础(译文)

DDL

Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:

CREATE - to create objects in the database
ALTER - alters the structure of the database
DROP - delete objects from the database
TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
COMMENT - add comments to the data dictionary
RENAME - rename an object
译：

数据定义语言(DDL)语句用来定义数据库结构或模式。例如：

create-创建数据库对象
alter-修改数据库的结构
drop-从数据库中删除对象
truncate-移除表中的所有记录，包括分配给记录的空间也会被移除
comment-为数据字典加一些评论
rename-给数据库对象重新命名

DML

Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

SELECT - retrieve data from the a database
INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - deletes all records from a table, the space for the records remain
MERGE - UPSERT operation (insert or update)
CALL - call a PL/SQL or Java subprogram
EXPLAIN PLAN - explain access path to data
LOCK TABLE - control concurrency
译：

数据操纵语言(DML)语句用来管理数据对象内的数据。例如：

select-从数据库中取回数据
insert-向表中插入数据
update-更新表中已经存在的数据
delete-删除表中的记录，分配给记录的空间会保留
merge-UPSERT操作(插入或更新)
call-呼叫一个PL/SQL或者java小程序
explain plan-解释数据的访问路径
lock table-控制并发

DCL

Data Control Language (DCL) statements. Some examples:

GRANT - gives user’s access privileges to database
REVOKE - withdraw access privileges given with the GRANT command

译：

数据控制语言(DCL)语句。

grant-授予用户一些对数据库的访问权限
revoke-回收用grant授予给用户的权限

TCL

Transaction Control (TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.

COMMIT - save work done
SAVEPOINT - identify a point in a transaction to which you can later roll back
ROLLBACK - restore database to original since the last COMMIT
SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use

译：